Technically there are five pelagic zones in the ocean, but the bottom one is estimated 90 percent unknown by people. The zones consist of the epipelagic zone, (surface to 200 meters below sea level (B.S.L.)) the mesopelagic zone, (200 meters B.S.L. to 1000 meters B.S.L.) the bathypelagic zone, (1000 meters B.S.L. to 4000 meters B.S.L.) the abyssopelagic zone, (4000 meters B.S.L. to the ocean floor). Some consider the hadopelagic zone part of the list and it is located in trenches deeper than the ocean floor. Some marine biologists also define the hadopelagic zone to be from 6000 meters B.S.L. to the ocean floor, not only in trenches.
Answer provided by Beau Fredericks, Billings West High School